Vulcanization process and product



- Patented Mar. 29, 1927.

UNITED STATES PATENT OFFICE.

PAUL I. MUIRBILL, PLAINFIELD, NEW JEBQEYQASSIGNOB TO B. '1. VANDERBILT- oo.,' me, or NEW YORK, n. Y., A conroan'rrou ormaw roux.

'VULCANIZATION PROCESS AND PRODUCT.

No Drawing. Original application filed September 30, 1925, Serial a... 59,573. Divided and this application filed August as, 1926. Serial No. 1aa,'a24.

a This invention'rela'tes to the vulcanization of rubber and includes the new vulcanization process as well as'the new vulcanization products.

0 According to the present invention, the, 'vulcanization is carried out with the addition-to the rubber of sulfurand of organic selenium compounds containing the roup -CSS, these selenium compounds eing 10. aetiveboth as vulcanizing' agents and as ac celerators of vulcanization.

The new organic selenium compounds used in the process of the present invention and in making the new vulcanized products of w the invention have the following general formula (CSS),Se, and they may contain a nitrogen, oxygen or carbon joined to the carbon of the above formula. Among the new vulcanizing agents which are particularly valuable for use in carrying out'the invention are the selenium salts or come pounds of diethyland dimethyldithiocarbamic acid of the general formula W (RRNESSLSe, where R and R represent simple or substituted hydrocarbon radicals which may be the same or different radicals,

such as methyl. ethyl, phenyl, benzyl, etc.,

or where RR'N represents piperidyl, etc.

Similiar selenium com ounds can be derived from the xanthic aci s of the general 'formula (RO.CSS),Se and from dithioacetic,

' dithiobenzoic, etc., acids, of the general formula (EO.CSS)S6.

The new selenium compounds can be produced in accordance with the process more fully described in-my companion application Serial No. 59,571, filed September-30, 1925,

by the action of a soluble selenite such as sodium selenite upon the sodium salt of the dithioacid, with the addition of a mineral or-organic acid such as hydrochloric acid.

The selenium diethyland dimethyldithiocarbamates may be produced, for example,

the reaction of the sodium d1methyl or 'diethyldithiocarbamate 4. mole.) u' on so' dium selenite (1 'mol.) and 6 mole. o h dro- .chloric acid. The selenium diethyldithiocarbamate. is readil soluble in carbon bisulfide and crystal i'zes' therefrom on the' addition of benzol. Whenthus crystalhzed The corresponding. dimethyl compound is a yellowish powder melting at about 163- 165C. and is so sparingly soluble in the usual organic solvents that it is difficultly illustrate the invention, the example giving the results obtained with the use of the new selenium compounds as accelerators in the following mix Pale crepe 100 Whiting 50 Zinc oxide 5 Sulfur d The selenium dimethyl or diethyldithio- I carbamate was used to the extent of on the rubber. The compounds were vulcanized at 'diiferent temperatures and pressures for difi'erent periods of time with the results indicated in the following tabulation. In the following table, the first column shows the time of cure in minutes and the steam pressure employed; the second column shows the tensile strength and elongation obtained with compounds containing on the rubber of selenium diethyldithiocarbamate; and

the third column shows the tensile strength and elongation obtained with on the rubber of selenium dimethyldithiocarbamate.

, Tensile Tensile Time and temperature of cure and and stretch stretch 30 min. at 2.6 3440-690 45 min. was 3340-690 60 min. at 2.5 3700-685 15 min. at 10 3320-665 30min. at 10 2720-060 45 min. at 10 3520-665 10 min. at 20 3120-670 15 min. at 20 3010-635 30 min. at 20 3120-680 5 min. a't 401 3260-710 15 min. at 40 2830-700 30 min. ue 2690670 It will be seen that the vulcanization can accelerators in a pure gum stock. The compound used was as follows:

Pale crepe 100 Zinc oxide 5 Sulfur l Accelerator 0.25

Using selenium dimethyldithiocarbamate as the acceleratonfthe following results were obtained:

t 12 5 min. at 141 C. (40 lbs.) 30 min. at 141 C. (40 lbs.)

From these examples it will be seen that the new organic selenium compounds used in the process of the present invention "are rapid in their action, causing cures at low temperature and in a short time, and that the stocks are not injured by longer exposure to heat, i. e., do not overcure readilv.

The new vulcanized products have improved properties and are characterized by containing selenium as well as sulfur therein, together Iith products of reaction of the organic selenium compounds.

This application is a division of my prior application Serial Number 59,573, filed September 30, 1925.

I claim:

1. The method of vulcanizing rubber which comprises subjecting the rubber to vulcanization with the addition thereto of an organic selenium compound containing the following group CSS- as an acceleravulcanization with the addition thereto ofan organic selenium compound of the following general composition :-Se( SSC- as'an accelerator together with sulfur.

3. The method of vulcanizing rubber which comprises subjecting the rubber to vulcanization with the addition thereto of an organic selenium compound of the following general. formula :(RRNCSS) 8c, where R and R are hydrocarbon radicals, as an accelerator together with sulfur.

4. The method of vulcanizingz rubber which comprises subjecting the rubber to vulcanization in the presence of selenium dialkyldithiocarbamate as an accelerator together with sulfur.

5. The method of vulcaniz'ing, rubber which comprises subjecting the rubber to vulcanization in the presence of selenium diethyldit-hiocarbamate as an accelerator together with sulfur.

6. New vulcanized rubber products vul canized with the addition thereto before vulcanization of sulfur and an organic selenium compound containing the following group 7 New vulcanized rubber products vulcanized with the addition thereto before vulcanization of sulfur and an organic selenium compoundof the following general compcsi tion,:- Se(SSC-) 8. New vulcanized rubber products vulcanized with the addition thereto before vulcanization of sulfur and an organic selenium compound of the following general formula: (RR'NGSS) Se, where R and R are hydrocarbon radicals.

9. New vulcanized rubber products vul canized in the presence of sulfur and selenium dialkyldithiocarbamate. 10. New vulcanized rubber products vul canized in the presence of sulfur and selenium diethyldithiocarbamate.

In testimony whereof I aflix my signature.

PAUL I. MURRILL.

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